Process for preparing lactones



Patented Sept. 28, 1948 2,450,133 PROCESS FOR IREPABING LAGTONES Hugh J Hagemeyer, Jr., signor to Eastman Kodak Kingsport, Tenn., as-

Company, Rochester,

N. Y., a corporation of New Jersey No Drawing. Applic Serial No.

ation July 12, 1947,

16 Claims. (01. zone-s44) This invention relates to a process for preparing fl-lactones, i. e. lactones of {i-hydroxycarboxylic acids, from ketenes. and aldehydes, ketones, diketones and keto carboxylic esters. Staudinger first showed that a keto ketene, such as diphenyl'lretene, added to aldehydes or ketones to give fiactones, (1911) and Ann. 3.80, 243 (1911). Staudinger also showed the addition of diphenyl ketene to unsaturated ketones, and isolated diolefins from the reaction mixture. Ann. 401, 263 (1913).

Aldo ketenes, on the other hand, are relatively unstable as compared with keto ketenes and dimerize rapidly, under ordinary conditions of temperature and pressure. In the absence of a catalyst, aldo ketenes do not condense with carbonyl compounds, but form the dimer instead. With aldehydes, the ketene dimers react to form unsaturated ketones. See Boese, United States Patent 2,108,427, dated February 15, 1938,

Kllng in United States Patent 2,356,459, dated August 22, 1944, has shown that ketene (CH2=C=O) reacts with aldehydes or ketones to give fl-lactones, in the presence of Friedel- Crafts type of catalysts.

I have now found that, in the presence of at least one metal fiuoborate represented by the formula:

where X is a divalent metal selected from the group consisting of zinc, lead, ferrous iron, nickel, stannous tin, copper and cadmium, ketenQS (both aldo and keto ketenes) react with carbonyl compounds selected from the group consisting of aldehydes, ketones, diketones and keto carboxylie esters to give fi-lactones.

The-catalysts of my process are superior to the Friedel-Crafts type of catalyst, in that the catalysts of my process are not affected by the presence of water. Friedel-Crafts type of catalysts are easily inactivated and destroyed by water, whereas the metal fluoborates can be conveniently employed in the form of a forty to fifty percent solution in water. The metal fluoborate catalysts are particularly advantageous where ketene (CH2 =C=O) is prepared by pyrolysis of acetic acid, since water is formed in the pyrolysis and small amounts of water are carried along with the ketene unless especial means are employed to free the ketene from all water. The metal fluoborates are also particularly advantageousin the preparation .of'the fi-lactone of {3- hydroxypropioni'c acid (hydracrylic acid) where paraformaldehyde is used as a source of formaldehyde, because commercial paraformaldeliyde contains as high as 5% of water.

It is, accordingly, an object of my invention to provide an improved process for preparing lactones. Other objects will become hereinafter.

In accordance with my invention, I prepare 5- lactones by reacting a ketene (either an aldo or a keto ketene) with an aldehyde, a ketone, a diketone, or a keto carboxylic ester, in the presence of at least one metal fluoborate represented by the general formula shown above.

The ketenes which are advantageously employed in practicing my invention can be represented by the following general formula:

C=C=O R1 wherein R and R1 each represents a hydrogen atom, an alkyl group (i. e. especiall methyl and ethyl groups, i. e. alkyl groups of the formula CnI'I2'n+1 wherein n represents a, positive integer of from 1 to 2) or anaryl group (especially a phenyl group, i. e. a CeHe-grollp). Although my invention is directed primarily to a process involving ketene (CH =C=O), any aldo ketene or any keto ketene can be employed. Typical aldo ketenes include ketene, methyl ketene, ethyl ketene, etc. Typical keto ketenes include dimethyl ketene, diethyl ketene, dlphenyl ketene, methyl phenyl ketene, etc.-

The .aldehydes which are advantageously employed in practicing my invention can be represented by the following general formula:

o=0 Rf wherein R2 represents an alkyl group (especially methyl, ethyl, isopropyl, n-propyl, n-butyl, isobutyl, secondary butyl and tertiary butyl groups, i. e. an allryl group of the formula CnH2n+1 wherein n represents a positive integer of from 1 to 4), an aralkyl group (especiall benzyl or fi-phenylethyl), and an aryl group (especially a monocyclic aryl group of the benzene series, e. g. phenyl, rn-tolyl and p-tolyl). My new process is especially useful for the preparation of B-lactones from aldehydes of the above general formula wherein R2 represents a hydrogen atom or a methyl group.

The ketones which are advantageously emapparent ,3 ployed in practicing my invention can be represented by the following general formula:

c=o R4 wherein R3 represents an methyl, ethyl, isopropyl, n-propyl, n-butyl, isobutyl, secondary butyl and tertiary butyl groups, 1. e. an alkyl group of the formula CnH2n+1 wherein n represents a positive integer of from 1 to 4) an aryl group (especially a monocyclic aryl group of the benzene series, e. g. phenyl, m-tolyl and p-tolyl), or an aralkyl group (especially benzyl and fl-phenylethyl), and R4 represents an alkyl group (especially methyl and ethyl groups) an aryl group (especially a monocyclic aryl group of the benzene series, e. g. phenyl, m-tolyl and.ptolyl) or an aralkyl group (especially benzyl and [i-phenylethyl). M new process is especially useful for the preparation of c-lactones from the above-formulated ketones wherein R4 represents a methyl group. p

The diketones which are advantageously employed in practicing my invention can be represented by the following general formula:

wherein R5 and Rs each represents an alkyl group (especially a methyl, an ethyl, or an n-propyl group) and m represents a positive integer of from 1 to 3.

The keto carboxylic esters which are advantageously employed in practicing my invention. can be represented by the following general formula:

phenone, methyl benzyl ketone, p-methylacetophenone, diacetyl, dipropionyl, di-n-butyryl, diisobutyryl, acetyl acetone, hexanedione 2,4, methyl pyruvate, ethyl pyruvate, methyl acetoacetate, ethyl acetoacetate, n-propyl acetoacetate, n-butyl acetoacetate, ethyl levulinate, etc.

The quantity of metal fluoborate catalyst employed can be varied and optimum concentrations are usually a function of the reactants employed.

Higher concentrations of catalyst can be employed, although ordinarily there is no advantage in doing so. The metal fiuoborates are advantageously employed in aqueous solution, e. g. 40

to 50% (by weight) of metal fluoborate.

Where the aldehyde, it is carbonyl compound employed is an advantageous ordinarily to add the alkyl group. (especially which are liquid at ketene and the aldehyde simultaneously and in equimolecular proportions to the catalyst or to a medium containing the catalyst. Where the carbonyl compound employed is a ketone, diketone or a keto carboxylic ester, the ketene is ordinarily advantageously added to. the ketone or lcetc carboxyl ic ester containing the-catalyst.

Advantageously my new process is carried out in a solvent for the reactants, i. e. an organic liquid which dissolves both the ketene and the aldehyde, ketone, diketone or keto carboxylic ester, and Which is relatively inert to the reactants. Suitable solvents include the dialkyl ethers which are liquid at 10 C., e. g. diethyl ether, ethyl isopropyl ether, diisopropyl ether, ethyl n-butyl ether, methyl n-propyl ether, etc., cyclic ethers 10 0., e. g. 1,4-dioxane, chlorinated hydrocarbons which are liquid at 10 0., e. g. chloroform, carbon tetrachloride, ethylidene dichloride, ethylene dichloride, etc., hydrocarbons whichare liquid at'10 C., e. g. benzene, toluene, etc.

In the case of thelower aldehydes, such as formaldehyde and acetaldehyde, ketones which are liquid at 10 C. can be employed as solvents because formaldehyde and acetaldehyde react with the ketenes much faster than do the ketones to give fi-lactones in accordance with my process.

I Acetone and methyl ethyl ketone are advantageously employed as solvents when formaldehyde or acetaldehyde is employed.

The ,B-lactones, themselves, are excellent solvents in which my process may be performed, and the lactone so used need not correspond to the lactone being formed. However, for practical purposes, it is desired to produce a relatively pure lactone, and a .lactone corresponding to the lactone being formed is used. If the lactone is to be used in the preparation of synthetic resins, polymers, etc., it may bedesired to produce a lactone mixture, since such a mixture can be used directly Without purification.

The temperature of my process may likewise be varied according to the type of compound being reacted. Care should be taken to avoid too rapid an elevation of temperature, since B-lactones readily lose carbon dioxide and form unsaturated compounds. The temperature used may be as low as 40' C. or as high as +50 0. However, it is generally preferred to use temperatures within the range of 0 C. to 40 C. Formaldehyde, for example, will react with ketene within the temperature range of 0 C. to 50 C. while acetone reacts at a temperature of from 5 C. to 40 C.

The process of my invention can be carried out batchwise or continuously (e. g. in the continuous manner described in the copending application of Hugh J. Hagemeyer, Jr., and Delmer C. Cooper, "SerialNo. 660,286, filed April 6, 1946). Where ketene (CH2=C=O) is prepared by the catalytic pyrolysis of acetic acid at reduced presaldehyd'es and ketones containing'olefinic or acetylenic bonds (e. g. crotonaldehyde, methyl isowares of the fi-lactones derived from keto carboxylic esters and diketones cannot be distilled, even under reduced pressure, without undergoing decarboxylation, i. e. loss of carbon dioxide, to give unsaturated compounds. Even the lower molecular weight ,B-lactones derived from lower molecular weight aldehydes and ketones, e. g. formaldehyde, acetaldehyde, acetone and ethyl methyl ketone,. have a tendency to polymerize when heated. With these lower molecular Weight [3-1actones, it is' advantageous 'to flash distill (i. e. distill rapidly under a low vacuum, the pump producing the vacuum having a capacity greater than the volume of vapor in the still) the reaction mixture and then to purify further the [ii-lactone by fractional redistillation under reduced pressure.

The following examples will serve to illustrate further the manner of practicing my invention.

Example I.--Lactone of p-hydromypropionic acid (B-propionolactoae) CH2-CHz -?=O A stain-less steel, jacketed reactor, 3 feet high and 2 inches inside diameter, was charged with 12 liters of methyl ethyl ketone in which had been dissolved 30 ml. of a 47.5% aqueous solution of zinc fluoborate. The ketone solution was circul ated through the reactor from bottom to-top and thence to the bottom through a returnline at a. rate of 2.2 gals. per minute, the solution being-cooled to C. by means of cold glycol circulated through the jacket of the reactor. Ke-v tene at. a rate of 4.6 gmS. per minute, and formaldehyde at a rate of 3.3 gms. per minute, were mixed immediately before entering the scrubber by means of a nozzle placed just below the screen supporting the packing, the pressure drop across the scrubber being maintained at 32. mm. As the volume of the reactor increased, the liquid overfiowed at the top, through a liquid-seal overflow into a line connected with a still.

The uncondensed vapors from the still, along with recovered methyl ethyl ketone, were led back to the reactor, and a partially purified c-propionolactone being attained. as a distillate. In an 8-hour run, 1570 gms. of formaldehyde and 2200 grns. of ketene were bled into the reactor. After redistillation of the fl-proprionolactone from a hot surface of 80 C. (2 mm. pressure), 2650 gins. of c-propionolactone, 13. P. 82-3 C. at 50 mm, N13 1.4130, were attained. (70.2% yield.) 1

Example II.--Lactone of c-hydroxybutyric acid (B-butyrolactone) An acetone solution containing 1% ferrous fluoborate was cooled to a temperature of 0 C. in: the manner described in Example I. Gaseous ketene and iacetaldehyde were then passed through the solution, the formed fi-butyrolactone he'ingv withdrawn continuously from the reactor. Over a 16-hour run, 320 grams of ketene and 330 grams of acetaldehyde were added, while the temperature of the reactor was maintained at 0-10 C. Upon neutralization of the reaction mixture, followed by a distillation under reduced pressure as described above, fi-butyrolactone (B. P. 54 C. at mm.) in 64% yield was obtained.

ketene and acetone in the I 6-. Example III.- -Lactone of p-hydhxflisovaikaricb acid, (p;methyl-p-batyrolactone) f cHio -oHzo=o In a manner similar to that described in the above examples, a1% solution of lead fiuoborate inacetone was cooled to 0 C. While maintaining the temperature, by cooling, at 0 to 10 C., a half a. mol. (21 grins.) of ketone per hour was passed through the solution, sufficient acetone being added to maintain an equimolar ratio of reactor. The crudev reaction mixture was neutralized with a dilute solution of sodium bicarbonate and then flashdistilled at C. under 2mm. pressure. tillation gave a 43% yield of B-rnethyl-B-butyrolactone 13.1. 55 C. at 10 min, N13 1.4126. Titra-- tion gave an equivalent weight of (theoretical 100).

Example IV.Lactone of B-carbocthomymethyl c-hydroxybutyric acid 0 611255 0 02115 CHs /CH2C=0 1 I A 1% solution of zinc fluoborate in ethyl acetoacetate was cooled to 0-10 C. While maintaining the temperature by cooling, between 0-10 C., 8d grams of ketene was passed in through a high speed stirrer. The catalyst wasneutralized with sodium bicarbonate dissolved in water. (In this example it was'preierred to decarboxylate the lactone and isolate the beta, gamma, unsaturated ester decarboxylation product as a measure'of the amount of lactone formation.)

The reaction mixture was refluxed at atmospheric'pressureuntil decarboxylation was complete. Decarboxylation temperature, 90-l10 C. grams of beta methylene ethyl butyrate, B. P. 20 mm. 54.5" C., N0 1.4400 was obtained. Reduction of the unsaturated ester with Raney nickel at 80 C. and 1000 p. s. i. gave a quantitative yield of ethyl isovalerate.

Example V.-Lactone 0 c-acet' Zmethyl-p-hydroacybutyric acid 0 0112543113 oHao-onlo=0 Example V I.-Lactone of fi-hydroary-el-hewenoic "acid oH;on='oH-oH-orrzo=o 0 2-00 grams of crotonaldehyde is added dropwise to a 1% solution of zinc fluoborate in 400 cc. of

diisopropyl ether at -10 C. Two moles of ketene are passed in through a, high speed stirrer over a 7 period of four hours. The catalyst is neutralized with sodium acetate and the solvent and unchanged crotonaldehyde are removed at 40 mm. The residue is decarboxylated and distilled to give six grams of isoprene and 42 grams of piperylene, B. P. 740, 41.4 C.

This corresponds to a 5% conversion to the ri-lactone and a 35% conversion to the fi-lactone.

In examples IV, V, and VI, deoarboxylation of the products therefrom were used as a measure of the lactone formation.

Other carbonyl-containing compounds may be used in my process to advantage. For example, when ketene is passed into butyraldehyde in which has been dissolved stannous fluoborate, ficapro-lactone having the formula:

CaHhCHCHsfi3=O is obtained in excellent yield (65-70%). Also if the acetone of Example III is replaced by acetophenone, the lactone of B-hydroxy-li-phenylbutyric acid of the formula:

CH5 CHr- -H,o=o

o is attained in 60% yield. Similarly, when furfuraldehyde replaces the acetaldehyde 0f Example II, the lactone of fi-(Z-furyl)-[3-hydroxypropicnic acid having the formula:

is obtained in excellent yield. Other carbonylcontaining compounds such at methyl acetoacetate, ethyl levulinate, biacetyl, etc., may likewise be used.

What I claim as my invention and desire to be secured by Letters Patent of the United States is:

1. A process for preparing fi-lactones comprising reacting at a temperature of below 50 C. and not less than 50 C., a ketene selected from the ketenes represented by the following general formula:

wherein R and R1 each represents a member selected from the group consisting of a hydrogen atom, a methyl group, an ethyl group and a phenyl (CeH5-) group, with a carbonyl compound selected from the group represented by the four general formulas:

C11H2n+1 wherein n is a positive integer from 1 to 4, and m is a positive integer from 1 to 3,'in the presence of at least one catalyst selected from the group of metal fiuoroborates represented by the following general formula:

wherein X represents a divalent metal cation selected from the group consisting of cadmium, copper, iron, nickel, lead, stannous tin and zinc. 2. A process for preparing p-lactones comprising reacting at a temperature of below 50 C. and not less than -50 C., a ketene selected from the ketenes represented by the following general formula:

wherein R and R1 each represents a member selected from the group consisting of a hydrogen atom, a methyl group, an ethyl group and a phenyl (C6H5) group, with a carbonyl compound selected from the group represented by the four general formulas:

0 0 Ru(-(CHz)n-|( )-Ru RT( /(CH2)m- ORa wherein R2 represents a member selected from the group consisting of a hydrogen atom; an alkyl group having the formula CnH2n+1 wherein n is a positive integer from 1 to 4; a benzyl group; a B-phenylethyl group; and a phenyl group, R3 and R4 each represents a member selected from the group consisting of alkyl groups having the formula C5H2n+1 wherein n is a positive integer from 1 to 4; a benzyl group; a B-phenylethyl group; and a phenyl group, R5, R6, R7, and Rs each represents an alkyl group having the formula CnHZn-H wherein n is a positive integer from 1 to 4, and m is a positive integer from 1 to 3, in the presence of from 0.1 to 3% by weight, based on the total reaction mixture, of at least one catalyst selected from the group of metal fluorobo-' rates represented by the following general formula:

X(BF4)2 wherein X represents a divalent metal cation selected from the group consisting of cadmium, copper, iron, nickel, lead, stannous tin and zinc.

3. A process for preparing fl-lactones comprising reacting at a. temperature of below 50 C. and not less than -50 C., a ketene selected from the ketenes represented by the following eneral formula:

o=o=o wherein R and R1 each represents a member selected from the group consisting of a hydrogen atom, a methyl group, an ethyl group and a phenyl (CeH5) group, with a carbonyl compound selected from the group represented by the four general formulas:

copper, iron,

wherein R2 represents a member. selected from the group consisting of a hydrogen atom; analkyl group having th'eformula CnHZn-j-l wherein n is a positive integer from 1 to '4; a benzyl group; a B-phenylethyl group; and a phenyl group, R3 and R4 each represents a member selected from the group consisting of alkyl groups having the formula CnH2n+1 wherein n is a positive integer from 1 to 4; a benzyl group; a p-phenyletrhyl group; and a phenyl group, R5, R6, R1, and Rs each represents an alkyl group having the formula .CnH2n+1 wherein n is a positive integer from 1 to 4, and m is a positive integer from l to ,3, in the presence of from 0.1 to 3% by weight, based on the total reaction mixture, of at least one catalyst selected from'the. group of metal fluoroborates represented 'by' the following generalformula:

X(BF,4)2

wherein X represents a divalent metal cation selected from the group consisting of cadmium, nickel, lead, stannous tin 1, and zinc, in the presence of a solvent selected from the group consisting of acetone, :methyl ethyl ketone, and .a c-lactone corresponding to the lactone formed in the reaction.

4. Aprocessfor preparing afi-lactone comprising reacting, at a temperature of below 50 C. and not less than --50 C4; ketene (Cl-Iz==) with a carbonyl compound selected from the group represented by the following four general wherein R2 represents a member selected from the group consisting of a hydrogen atom, an alkyl group of the formula CnH2n+1 wherein n represents a positive integer of from 1 to 4, a benzyl group, a, p-phenylethyl group and a phenyl (CsH5-) group, R3 represents a member selected from the group consisting of an alkyl group of the formula CnH2n+1 wherein n represents a positive integer of from 1 to 4, R5 and Re each represents an alkyl group of the formula C1LH211.+1 wherein n represents a positive integer of from 1 to 3, R7 represents an alkyl group selected from the group consisting of methyl and ethyl groups, and RB represents a member selected from the group consisting of primary and secondary alkyl groups of the formula CHI-121M wherein n represents a positive integer of from 1 to 4, and m represents a positive integer of from 1 to 3, in the presence of at least one catalyst selected from the group of metal fluoroborates represented by the following general formula:

wherein X represents a divalent metal cation selected from the group consisting of cadmium, copper, iron, nickel, lead, stannous tin and Zinc.

5. A process for preparing a ,B-lactone which comprises reacting at a temperature of from -40 to +50 C. ketene (CI-I2=C=O) with an aldehyde having the formula:

o=o R2 wherein R2 represents a member selected from the group consisting of hydrogen, an alkyl group having the formula CnI'IZn+1 where n is a positive integer from 1 to 4, a benzyl group, a p-ph'enylethyl group, and a phenyl group in the presence of at least one catalyst selected from the group of metal fluoroborates represented by the following general formula:

wherein X represents a divalent metal cation selected from the group consisting of cadmium, copper, iron, nickel, lead, stannous tin and Zinc. 63. A process for preparing a p-lactone which comprises reacting at a temperature of from -40 to +50 C. ketene (CHz=C=O) with a ketone having the formula:

o=0 R4 wherein R3 and R4 each represents a member selected from the group consisting of an alkyl grouphaving the formula CnH2n+1 Where n is a positive integer from 1 to 4, a benayl group, a ,B-phenylethyl group,-and a phenyl group in the presence of at least one catalyst selected from the roup of metal ,fl-uoroborates[represented by the following general formula:

wherein X represents a divalent metal cation selected from the group consisting of cadmium, copper, iron, nickel, lead, stannous tin and zinc. '7! A process for preparing p-propionolaotone comprising reacting at a temperature of from 40 to +50 Q'ketene (CI-Iz=C=O) with formaldehyde inthe presence ofat least one catalyst selected from the group of metal fluoroborates represented by the following general formula:

wherein X represents a divalent metal cation selected from the group consisting of cadmium, copper, iron, nickel, lead, stannous tin and zinc.

8. A process for preparing p-propionolactone comprising reacting ketene (CHz=C=O) with formaldehyde in the presence of from 0.1 to 3% by weight, based on the total reaction mixture, of at least one catalyst selected from the group consisting of metal fluoborates represented by the formula:

wherein X is a bivalent metal catiton selected from the group consisting of cadmium, copper, iron, nickel, lead, stannous tin, and zinc, at a temperature of from 40 to +50 C.

9. A process for preparing fl-propionolactone which comprises reacting ketene (CH2=C=O) with formaldehyde in the presence of from 0.1 to 3% by weight, based on the total reaction mixture, of at least one catalyst selected from the group consisting of metal fluoborates represented by the formula:

wherein X is a bivalent metal cation selected from the group consisting of cadmium, copper, iron, nickel, lead, stannous tin, and zinc, at a temperature of 0 to +40 C. in the presence of a solvent for the reactants.

10. A process for preparing fl-propionolactone which comprises reacting ketene (CHFC=O with formaldehyde in the presence of from 0.1% to 3% by weight, based on the total weight of the reaction mixture, of zinc fluoborate, at a temperature of from 40 to +50 C.

11. A process for preparing fi-propionolactone which comprises reacting ketene (CH2=C=O) with formaldehyde in the presence of from 0.1% to 3% by weight, based on the total Weight of the reaction mixture, of zinc fiuoborate, at a temperature from to +40 C. in the presence of ,B-propionolactone as solvent.

12. A process for preparing p-propionolactone which comprises reacting ketene (CH2=C'=O) with formaldehyde in the presence of from 0.1% to 3% by weight, based on the total weight of the reaction mixture, of zinc fluoborate, at a temperature of from 0 to 40 C. in the presence of a solvent selected from the group consisting of acetone, methyl ethyl ketone, and fl-propionolactone.

13. A process for preparing ,B-propionolactone comprising reacting at a temperature of from 40 to +50 C. ketene (CI-IFC=) with formaldehyde in the presence of at least one catalyst selected from the group of metal fluoroborates represented by the following general formula:

wherein X represents a divalent metal cation selected from the group consisting of cadmium, copper, iron, nickel, lead, stannous tin and zinc, in the presence of a solvent selected from the group consisting of acetone, methyl ethyl ketone, and fl-propionolactone.

14. A process for preparing B-butyrolactone comprising reacting at a temperature of from 40 to +50 C. ketene (CH2=C=O) with acetaldehyde in the presence of at least one catalyst selected from the group of metal fiuoroborates represented by the following general formula:

borates represented by the following general formula:

X (BF4) 2 wherein X represents a divalent metal cation selected from the group consisting of cadmium, copper, iron, nickel, lead, stannous tin and zinc in the presence of a solvent selected from the group consisting of acetone, methyl ethyl ketone, and fi-butyrolactone at a temperature of to C.

16. A process for preparing fl-butyrolactone comprising reacting ketene (CH2=C=O) with acetaldehyde in the presence of from 0.1% to 3% by weight, based on the total weight of the reaction mixture, of ferrous fluoborate in the presence of a solvent selected from the group consisting of acetone, methyl ethyl ketone, and pbutyrolactone, at a temperature from 40 to +50 C.

HUGH J. HAGEMEYER, JR.

REFERENCES CITED UNITED STATES PATENTS Name Date Boese Aug. 14, 1945 Number e of Correction 4 tember 28,1948.

Certificat Sep on of the above HUGH J HAGEMEYER, JR.

r 'm the printed speeificatl at errors ppea a eotron as follows:

'me 37, for

2 Example Ill, for ketone read ketene; column 7,

line 52,0la'1m 8, for catltoh read cotton; column z 1; d Hz00 111 e read with these correction 'n the Pet t Office.

s therein that MS F. MURPHY, 7 Patents.

Assistant Gammissioner o 

